21. a. Corynebacterium Flashcards
Which virulence factor produced by Corynebacterium diptheriae is important in the pathogenesis of this infection?
Exotoxin
Responsible for disease as bacteria doesn’t spread but toxin does
What complications can arise from a diphtheria infection?
Myocarditis
Paralysis
Toxaemia
Death
What is the appropriate treatment for a child with diphtheria?
Antitoxin
Antibiotics
Alongside antibiotics and antitoxin, how else should a child with diphtheria be managed?
Contact prophylaxis
Inform parents that you will need to see the child again
Notify public health
Isolate the patient
What should you do before sending a diphtheria sample to the lab?
Call your local diagnostic facility and consult a clinical microbiologist
What does corynebacteria look like under the microscope?
Gram + bacilli arranged in L or V shapes
What are some metabolic features of corynebacterium?
Faculative anaerobic
Catalase +
No spores
How long is the incubation period for corynebacterium?
2-6 days
Where does corynebacterium colonise?
Skin
Upper respiratory tract
Genitourinary tract
How is corynebacterium spread?
Droplets
Who is at risk of c. diphtheriae?
Children
Unvaccinated
Overcrowding
What are the biotypes of c. diphtheriae?
Gravis and mitis
How is the toxigenicity of c. diphtheriae detected?
Elek test
tox gene on PCR
What types of diseases are caused by c. diphtheriae?
Pharyngeal and tonsillar
Cutaneous
How does a c. diphtheriae pharyngitis present?
Exudative with a thick, black, adherent pseudomembrane
Low fever
‘Bull neck’ oedema
What is the pseudomembrane in c. diph pharyngitis made up of?
Exudate
Bacteria
Fibrin
Dead cells
What is the presentation of a cutaneous c. diph infection?
Non-healing ulcer with a grey membrane
What complications are associated with c. diph infeciton?
Myocarditis leading to cardiac arrhythmia
Neuritis leading to respiratory paralysis
Pseudomembrane can obstruct airway
What samples are taken to diagnose a c. diph infection?
Nasal and pharyngeal swabs
What cultures is c.diph grown in?
Loeffler’s serum slope or potassium tellurite agar
How does c. diph appear on postassium tellurite?
Reduces tellurite to form black colonies
What drugs are given to manage c. diph infection?
Antitoxin which neutralises the unbound toxin
Penicillin or erythromycin
What non-drug management is used to help a c.diph infection?
Manage airway
ECG and enzymes to catch myocarditis
Neurology for neuritis
What form of c. diph is in the DTaP vaccine?
Formalin-inactivated diphtheria toxoid
